Definition: a Crustacean is a mostly aquatic group of arthropods of the class Crustacea including lobsters, crabs, shrimps and barnacles. They characteristically have a segmented body, an exoskeleton and paired jointed limbs. Like all arthropods, crustaceans have a hard external skeleton (exoskeleton). They have two pairs of antennae, a pair of mandibles, two pairs of maxillae (mouth parts used for eating) on their heads, a pair of appendages on each body segment (head, thorax, and abdomen) and a pair of compound eyes (usually on stalks).
9 Facts About Crustaceans:
1) The largest kind of Crustacean is the Giant Spider Crab found in the waters of Japan. It measures up to 12 feet (3.7 metres) across its outstretched claws.
2) The smallest Crustaceans such as water fleas can be smaller than 1/125 of an inch (0.2mm) long.
3) All Crustaceans have an exoskeleton which cannot grow so it must be moulted for the next to grow.
4) There are 44,000 different species of Crustaceans. Most of them live in the sea (marine) but some of them live in freshwater while others live on land.
5) The most well-known Crustaceans are Decapods. Decapods have ten legs, and species from this group include Lobsters, Prawns, Crabs and Crayfish
6) Live lobsters can be yellow, blue, orange, red (not usually, probably pigment displacement) and white, but almost never red (see before).they actually only turn red when they have been cooked!
7) Male fiddler crabs have one large claw which they wave in the air to impress females when trying to find a mate and to intimidate other males and predators. The waving of their claw is thought to resemble playing the fiddle (violin).
8) Lobsters have the ability to regenerate body parts (claws, legs, etc.) which they lose.
9) Some species are active predators, some are filter-feeders and others are scavengers. They may be free-living, sessile or even parasitic. Woodlice are the most terrestrial of the crustaceans. Although they tend to live in damp places, some species can survive in deserts. A number of crab species are semi-amphibious, returning to water only to breed.